The problem of output regulation, including reduction of line frequency components, in an isolated power supply unit (PSU) may be handled by either a single, relatively less efficient regulated DC/DC stage, or by the use of two conversion stages, e.g. an Intermediate Bus Architecture or Factorized Power stage utilizing a highly efficient unregulated isolated DC/DC converter (also referred to as a DC transformer, hereinafter interchangeably referred to as a ‘DCX’) together with a regulated, non-isolated DC/DC stage (D2D) either before or after the DCX.
Although the efficiency of the DCX/D2D combination (or vice versa) may be higher than the single regulated DC/DC stage, the overall efficiency is still less than that possible with a single DCX conversion stage. One problem with utilizing a single DCX stage is the possible transfer of variations in its input voltage to its output. Another problem with utilizing a single DCX stage is the possible output voltage variation with output load variation.